June 25, 2009
Canada researchers study heat effects on broiler hens
Researchers at the University of Alberta are working to better understand the effects of environmental temperatures on feed-restricted broiler breeder hens.
The ongoing study has quantified the impact that different environmental temperatures can have on the amount of feed birds that require to grow at a consistent rate, said the Poultry Science Association (PSA).
The research team aims to optimise reproductive performance of broiler breeders by manipulating their growth curves by fine-tuning feed allocations based on short-term weather forecasts.
Determining optimal feed allocation for restricted broiler breeders is a challenge because birds' energy requirements shift along with environmental temperatures, said project leader Dr Martin Zuidhof.
To avoid confusing a bird's metabolism, feed allocations must be increased gradually but frequently to meet target body weight gains without over- or under-compensating.
Broiler breeders maintain their body temperatures within a very precise range, but temperature fluctuations in breeder houses can significantly change the amount of energy available to the breeder for growth, Zuidhof said.
The team needs to quantify the relationship among the variables of feed, body and external temperature, and they've taken a big step forward, he said.
Based on data from their research, Zuidhof and his team has developed an equation specifying how a broiler breeder's maintenance energy requirement varies as a function of four variables - body weight, weight gain, external temperature and age.
Earlier research by Zuidhof and his team had determined diurnal core body temperature patterns in feed restricted broiler breeder pullets housed at different temperatures. The findings suggested that environmental temperature would have an important impact on the birds' daily metabolic requirements.
Environmental temperatures were found to have a large effect on maintenance requirements, which dramatically changes the amount of energy remaining to support growth.
Zuidhof said they hope the study will help commercial hatching egg producers to maintain steadier metabolic rates in broiler breeders, which in turn will help drive breeder productivity.
